head

A cross-platform head clone written in Rust.

head is a command-line utility that outputs the first N lines (default 10) or bytes from standard input or one or more files. It supports all standard GNU head features including multiple file support with headers and negative count syntax.

See also: iwatakeshi/tail — a companion cross-platform tail clone written in Rust.

Features

• Line-based output (-n): Output the first N lines (default 10)
• Byte-based output (-c): Output the first N bytes
• Negative count (-NUM): Use -n -NUM or -c -NUM to output all but the last NUM lines/bytes
• Legacy shorthand: -NUM is accepted as a shorthand for -n NUM (e.g. head -5 file)
• Multiple files: Process multiple files with automatic headers
• Header control (-q/-v): Suppress or force file name headers
• Size suffixes: Support for K, M, G, kB, MB, GB, etc.
• Zero-terminated (-z): Use NUL as line delimiter instead of newline
• Cross-platform: Works on Linux, macOS, and Windows

Usage Examples

# Display first 10 lines of a file (default)
head /etc/passwd

# Display first 20 lines from stdin
cat /path/to/file | head -n 20

# Display first 5 lines of a file
head -n 5 /etc/passwd

# Legacy shorthand for first 5 lines
head -5 /etc/passwd

# Display first 100 bytes
head -c 100 myfile.txt

# Display all but the last 5 lines
head -n -5 myfile.txt

# Display all but the last 100 bytes
head -c -100 myfile.txt

# Multiple files with headers
head -n 5 file1.txt file2.txt file3.txt

# Use size suffixes
head -c 2K myfile.txt    # First 2 KiB (2048 bytes)
head -c 1M myfile.txt    # First 1 MiB (1048576 bytes)

# Suppress headers with multiple files
head -q -n 5 file1.txt file2.txt

# Use NUL-terminated lines
head -z -n 5 myfile.txt

Full Usage

Print the first 10 lines of each FILE to standard output.
With more than one FILE, precede each with a header giving the file name.

With no FILE, or when FILE is -, read standard input.

Usage: head [OPTIONS] [FILE]...

Arguments:
  [FILE]...  Files to read from (optional, reads stdin if omitted or -)

Options:
  -c, --bytes <[-]NUM>      Print the first NUM bytes of each file; with the leading '-',
                            print all but the last NUM bytes of each file
  -n, --lines <[-]NUM>      Print the first NUM lines instead of the first 10; with the
                            leading '-', print all but the last NUM lines of each file
  -q, --quiet               Never print headers giving file names
  -v, --verbose             Always print headers giving file names
  -z, --zero-terminated     Line delimiter is NUL, not newline
  -h, --help                Print help
  -V, --version             Print version

Size Suffixes

NUM may have a multiplier suffix:

• b = 512
• kB = 1000, K / KiB = 1024
• MB = 1,000,000, M / MiB = 1,048,576
• GB = 1,000,000,000, G / GiB = 1,073,741,824
• TB = 1,000,000,000,000, T / TiB = 1,099,511,627,776

Building

# Build release binary
cargo build --release

# Run tests
cargo test

# Run linter
cargo clippy

# Format code
cargo fmt

License

MIT